This invention relates generally to the electrical plug receptacle units and particularly to multiple electrical plug receptacle units adapted to be attached to a wall-mounted receptacle.
In households, offices, and the like, electrical plug receptacles are generally mounted in a wall such that the receptacle is approximately co-planar with the wall. This configuration requires that any electrical plug be inserted in a direction generally perpendicular to the wall. As a result, the plugs, and the cords which are generally integral thereto, occupy a significant amount of space in front of the wall so that furniture, appliances, etc. cannot be placed immediately adjacent to the wall. Further, most wall-mounted electrical receptacles are duplex in form, that is, the receptacle will accommodate only two plugs. On occasion, it may be desirable or necessary for more than two plugs to be coupled to the electrical power at a particular electrical receptacle. In such circumstances, it has been common for plug receptacle adapter devices to be employed Such adapter devices typically engage one or both electrical outlets of a standard wall-mounted duplex electrical plug receptacle and provide three or more outlets on an outer surface thereby increasing the number of plugs which can obtain power from a single duplex receptacle. The use of such adapters generally contributes to the space problem addressed previously. Further, such adapter units contribute to an unsightly pile of spaghetti like appearance to the various cords attached to the plugs inserted in the receptacle and adapter.
In addition to space and appearance problems, prior art adapters often also have some structural features which contribute to some functional or performance problems For example, many electrical plug receptacle adapter units employ a single unitary metal element to form a prong of the adapter unit for insertion into the wall-mounted receptacle and the contact blades necessary to contact electrical plugs inserted into the adapter unit While such unitary construction may have some advantages, it has been observed that upon the insertion of a plug into the receptacle adapter unit, the insertion force is transmitted directly to the blade inserted in the wall-mounted receptacle and can contribute to blade contact failure. The single unitary metal units, if designed to contact both duplex outlets of the wall mounted receptacle, can act to defeat a selectively switched arrangement present in the wall mounted receptacle.
Additionally, in order to lower costs, the electrical contacts within the receptacle adapter unit have typically been situated within an adapter unit solely by means of the insulative material making up the exterior or body of the adapter unit. Construction of such a unit is accomplished by forming cast units which consume a great deal of insulating material. Alternatively, such units can be constructed for piece-wise assembly using a ready formed body, but often such units are susceptible to breakage when experiencing the insertion forces applied during the insertion of electrical plugs into the adapter unit. Additional problems have been observed with prior art electrical receptacle adapter units which, although not enumerated here, are in fact solved by the construction and use of a multiple electrical plug receptacle unit in accordance with the present invention.